he State must act fast to enforce indoor lock downs and effective ‘social and physical distancing’ norms through media, social help groups, vigorous public announcements and by applying force, if that becomes necessary.(REUTERS)
he State must act fast to enforce indoor lock downs and effective ‘social and physical distancing’ norms through media, social help groups, vigorous public announcements and by applying force, if that becomes necessary.(REUTERS)

Mutant strains emphasise the need for strict controls

It is important to keep the viral load in check so that the natural benefits India’s population enjoys of broad-based immunity can be best made use of
By Narinder K Mehra
UPDATED ON DEC 31, 2020 05:43 AM IST

The Sars-CoV2 that causes Covid-19 in humans is a positive single-strand RNA virus that jumped species to humans in 2019. Mutations within RNA viruses, including those in coronaviruses, occur frequently because of the need for adaptation to the new host and for survivability. While a large majority of such mutations are generally neutral, others may either be advantageous or deleterious to the virus. Mutations that are highly deleterious get deleted rapidly from the population, while those that are only slightly deleterious may be retained, albeit transiently.

The 21st century has already seen three coronaviruses, of which the Sars-CoV2 has shown higher transmissibility and infectivity due to an important mutation at position 614 of its genome whereby an amino acid (AA) aspartic acid changes to glycine at this position of the Spike protein of the virus (D614G). Amino acids are the structural units that combine to form proteins. The latter are recognised as antigens by the host, evoking specific immune responses.

Recently, another mutation, namely N501Y, has been recorded in the United Kingdom (UK), leading to a change of AA asparagine to tyrosine at position 501 and linking it to further increased transmissibility.

This has caused immense concern, especially at a time when the emergence of vaccines had brought cheer and hope for the humanity. The new UK strain designated as VUI2020/12/01 (variant under investigation, year 2020, month 12, variant type 01) has recorded over 20 mutations, mostly silent, causing no change in the protein.

Biologically, mutations represent steps in virus evolution under selection pressure of the host immunity. Experts in evolutionary biology view these as a system evolved by the virus to escape immunity or to enhance transmissibility. As the virus replicates, mutations happen in its genes continually through a process called “antigenic drift”, causing minor changes in the surface protein. However, these small changes could accumulate over time, and result in newer viruses that could become antigenically different such that the existing antibodies mounted by the host immune system to the original virus fail to recognise and neutralise them.

As of date, there is little information on the pathogenicity (ability to cause disease) and immunogenicity (ability to provoke immune response) of the new UK variant. The New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) in UK has reviewed the new strain and found four interesting features.

One, its growth rate is ~71% higher than other variants, and two, the R-value shows an absolute increase between 0.39 and 0.93. The R value represents reproduction number and indicates an average number of secondary infections caused by an infected case. Value >1 suggests transmission to a number of individuals and higher spread of the disease. Three, the cycle threshold or CT value in the RT-PCR test suggests a decrease of about 2 and, four, the viral load suggests 0.5 increase in median log10 in new 501Y strain as compared to the original 501N. However, despite higher transmissibility, the new strain has not shown severe complications. It is also unlikely that it won’t be responsive to the already developed coronavirus vaccines, although relevant data needs to be generated on that front.

The important question is why and how do these mutations occur and whether there is a role for host immunity in driving them? More importantly, could antibody treatment or other therapies have an influence in the process? The preprint of a recently submitted paper to medRxiv portal by the group in Cambridge, UK, led by Dr Ravinder Gupta, has focused exactly on these issues. The study is based on a single case report of an immune-compromised individual with chronic SARS-CoV-2 infection, lasting over 100 days and treated with three units of convalescent plasma, two on day 65 and one on day 95 in an effort to neutralise the virus and treat the chronic infection.

The virus was detectable in the patient in all nasal swab samples collected at least 23 times over a period of 101 days, despite the plasma therapy. The authors investigated the SARS-CoV-2 evolution and found important changes in its genome caused by two new mutations in the spike protein, one a deletion of AA Histidine and Valine at positions 69 and 70 and, two, one AA replacement at position 796 (D796H). The authors state that while the two mutations did not increase infectivity of the virus, these might have been responsible for decreased sensitivity of the patient to convalescent therapy.

Being a single case report, the results of the study cannot be generalised. However, it raises the important issue of generation of “escape mutants” of the virus in patients with persistent infection. The virus escaped attack by neutralising antibodies present in the convalescent plasma. The important lesson is to perform careful monitoring of such newer strains both for their transmissibility and potential to evade vaccine-mediated immunity. The emergence of new mutants of the coronavirus further emphasises the need for observing infection-control practices even more strictly and until such time that herd immunity develops.

Dr Narinder Kumar Mehra is Indian Council of Medical Research Emeritus Scientist (Hon) and former Dean of the All India Institute of Medical Sciences, New Delhi

The views expressed are personal

SHARE THIS ARTICLE ON
app
Close
How do we address this cyclical pattern of hailing and rubbishing financiers? It is time for an honest review of the entire issue (Getty Images/iStockphoto)
How do we address this cyclical pattern of hailing and rubbishing financiers? It is time for an honest review of the entire issue (Getty Images/iStockphoto)

The policy landscape around digital and physical micro-lending

By Amol Agrawal
UPDATED ON JAN 25, 2021 06:08 AM IST
In 1870s, a similar backlash emerged in Poona and Ahmednagar districts of the Bombay presidency. The agriculture boom in the early 1860s led farmers to take loans from moneylenders
Close
A tiny tax on stock market transactions can help fund India’s vaccination drive without burning a hole in the wallets of stock market investors and give the government headroom for other expenditure to help save lives (AFP)
A tiny tax on stock market transactions can help fund India’s vaccination drive without burning a hole in the wallets of stock market investors and give the government headroom for other expenditure to help save lives (AFP)

Vaccinating all Indians, for free

By Praveen Chakravarty
UPDATED ON JAN 25, 2021 06:08 AM IST
The markets are at an all-time high. Impose a Covid-19 surcharge on transactions and use it for vaccination
Close
Why is it that, despite the government displaying its willingness to take a step back, the matter was not resolved? (PTI)
Why is it that, despite the government displaying its willingness to take a step back, the matter was not resolved? (PTI)

Farm protests: The costs of a prolonged standoff

By Shashi Shekhar
UPDATED ON JAN 25, 2021 06:08 AM IST
The government has extended an olive branch. The farmers must respect this and reciprocate. The tone set on Saturday should pave the way for a permanent solution.
Close
Pushing against the climate crisis — in spite of the terrible fire and hurricane damage — was his way of putting the economy before all else. This is what Biden-Harris will have to overcome with smart policies and even smarter communication. (AFP)
Pushing against the climate crisis — in spite of the terrible fire and hurricane damage — was his way of putting the economy before all else. This is what Biden-Harris will have to overcome with smart policies and even smarter communication. (AFP)

On climate, what the US needs to do

By Sunita Narain
UPDATED ON JAN 24, 2021 06:25 AM IST
Joe Biden has done well to rejoin the Paris accord. But his administration will have to overcome Trumpism, take responsibility for historic emissions, and change energy consumption patterns at home
Close
The JPC, hence, has a daunting task ahead, balancing the needs of State security against individual privacy. Giving entry to security agencies will compromise the encryption grid and data of millions. The State has to collaborate with tech giants in using the meta-data more meaningfully and for meeting other requirements without breaking the encryption. (Getty Images/iStockphoto)
The JPC, hence, has a daunting task ahead, balancing the needs of State security against individual privacy. Giving entry to security agencies will compromise the encryption grid and data of millions. The State has to collaborate with tech giants in using the meta-data more meaningfully and for meeting other requirements without breaking the encryption. (Getty Images/iStockphoto)

Data bill: The security vs privacy debate

By Yashovardhan Azad
UPDATED ON JAN 24, 2021 06:26 AM IST
The Data Protection Bill also does not touch upon State surveillance methods. Who watches over the watchers? How can an officer of the same rank give permission to another for snooping? And how can another in the same system oversee its justification?
Close
The massive sacrifice of hundreds of Secret Service officers of Netaji Subhas Chandra Bose’s Indian National Army remains a secret and an enigma. On the 125th anniversary of Netaji’s birth, I appeal to the nation to document and recognise these sacrifices (HT PHOTO)
The massive sacrifice of hundreds of Secret Service officers of Netaji Subhas Chandra Bose’s Indian National Army remains a secret and an enigma. On the 125th anniversary of Netaji’s birth, I appeal to the nation to document and recognise these sacrifices (HT PHOTO)

The secrets of Netaji’s secret service

By Amit Mitra
PUBLISHED ON JAN 22, 2021 06:49 PM IST
The Indian National Army’s Secret Service men remain unrecognised, despite their sacrifices during the freedom struggle. We must revere them
Close
Prime Minister Imran Khan has contended that Pakistan's economy has made a remarkable turnaround.(Facebook/ImranKhanOfficial)
Prime Minister Imran Khan has contended that Pakistan's economy has made a remarkable turnaround.(Facebook/ImranKhanOfficial)

Imran Khan jumped the gun. This time, over Pakistan’s economic turnaround

UPDATED ON JAN 22, 2021 03:51 PM IST
  • Pakistan's GDP growth had slowed down much before the coronavirus outbreak, growing by 1.9% in 2019 as compared to a decade-high of 5.8% the previous year when Imran Khan's Pakistan Tehreek-e-Insaf came to power.
Close
While social media has the ability to democratise politics, it can also silence voices. This is troubling (AFP)
While social media has the ability to democratise politics, it can also silence voices. This is troubling (AFP)

The democratic dilemma posed by social media

By Manjari Chatterjee Miller
UPDATED ON JAN 22, 2021 06:20 AM IST
The banning of Trump and others from Twitter and Facebook, and the shutdown of Parler made clear that the power to silence voices, whether of the one or of millions, lies with just three men on the planet – Mark Zuckerberg of Facebook, Jack Dorsey of Twitter, and Jeff Bezos of Amazon. No wonder defending democracy will be a huge and unenviable task for President Biden’s team.
Close
The Supreme Court, in 2019, acknowledged that internet access is integral to the right to freedom of speech and expression while adding that any restriction on internet access must pass the test of proportionality, and suggested the evolution of a rules-based mechanism to govern the internet. (Getty Images/iStockphoto)
The Supreme Court, in 2019, acknowledged that internet access is integral to the right to freedom of speech and expression while adding that any restriction on internet access must pass the test of proportionality, and suggested the evolution of a rules-based mechanism to govern the internet. (Getty Images/iStockphoto)

Putting the consumer at the centre of Digital India

By Lloyd Mathias
UPDATED ON JAN 22, 2021 06:21 AM IST
One way to empower consumers is by creating mechanisms to ensure inter-operability, by making it easier to switch services from one platform to another. In telecom, interoperability is implemented. However, in the internet space, and more prominently in the app space, consumers do not have this choice.
Close
Project finance economies have different imperatives from working capital economies. They need investment to fill the gaps in their infrastructure and lack the resources to do so (Pratik Chorge/HT PHOTO)
Project finance economies have different imperatives from working capital economies. They need investment to fill the gaps in their infrastructure and lack the resources to do so (Pratik Chorge/HT PHOTO)

The working of a ‘project finance economy’

By Janmejaya Sinha
UPDATED ON JAN 22, 2021 06:19 AM IST
It is time to question neo-classical economic precepts on deficit and inflation for an economy of India’s nature
Close
Their success highlights the depth and strength of talent in the country (PTI)
Their success highlights the depth and strength of talent in the country (PTI)

Courage, calibre, character: India’s greatest series win

By Ayaz Memon
PUBLISHED ON JAN 20, 2021 08:07 PM IST
The experienced pros and newcomers combined to prove a point to themselves, the opponents and the world. And created history
Close
The Centre ensured the supply of drugs with equitable and integrated access (REUTERS)
The Centre ensured the supply of drugs with equitable and integrated access (REUTERS)

Managing drug security effectively in times of a pandemic

By Sudhansh Pant
UPDATED ON JAN 20, 2021 09:19 PM IST
The Centre’s strategy to ensure sufficient access, monitor stocks and distribution, issue approvals, maintain seamless supply chain of drugs, effectively communicate with stakeholders, and evolve a dynamic Clinical Management Protocol (CMP) has contributed significantly to India’s Covid-19 management success
Close
A new report by Chatham House describes India as UK’s ‘rival’ or ‘at best, an awkward counterpart’ on par with Russia, Turkey and Saudi Arabia. It also weighs in against the idea of expanding G7 to include India (Getty Images)
A new report by Chatham House describes India as UK’s ‘rival’ or ‘at best, an awkward counterpart’ on par with Russia, Turkey and Saudi Arabia. It also weighs in against the idea of expanding G7 to include India (Getty Images)

Is ‘Global Britain’ inimical to India?

By Syed Akbaruddin
UPDATED ON JAN 20, 2021 09:10 PM IST
There are disturbing signals from both segments of British polity and civil society. India will need to assess the UK’s position carefully
Close
Pakistan's opposition parties had united last year under the aegis of Pakistan Democratic Movement to launch coordinated attacks on Prime Minister Imran Khan(AFP)
Pakistan's opposition parties had united last year under the aegis of Pakistan Democratic Movement to launch coordinated attacks on Prime Minister Imran Khan(AFP)

Imran Khan gets squeezed between shrinking economy and proactive opposition

UPDATED ON JAN 20, 2021 05:48 PM IST
  • Differences between China and Pakistan over funding of CPEC's biggest railway project spotlights the growing pressures on PM Imran Khan on the economy front
Close
There is evidence to indicate that the PLA's work and engineering force deployed to upgrade infrastructure in occupied Aksai Chin moved back after completion of work last month
There is evidence to indicate that the PLA's work and engineering force deployed to upgrade infrastructure in occupied Aksai Chin moved back after completion of work last month

India should be wary of Chinese mind games

UPDATED ON JAN 13, 2021 12:31 PM IST
  • Withdrawal from the vast Tibetan and Xinjiang military region means little in an era of stand-off weapons and long-range missiles. The Chinese PLA has capacity to deploy troop divisions within a week with metalled roads and optical fibre cables up to the last military post and advanced landing grounds (ALGs) all along the LAC.
Close
SHARE
Story Saved
OPEN APP